The determination of the bearing capacity of sub-soils using the conventional Plate Load Testing Techniques usually involves firmly grouted heavy reaction piles, H-beams, extremely heavy dead weights, slow-moving barges and tug-boats that are not only time – consuming but very expensive to employ. A Modified Plate Load Tester that comprises a 0.4064meter (16.00 inch) square base, a 0.2032meter (8.00 inch) diameter and 0.762m (2.50 feet) long cylindrical steel stem with a receptacle for load bearing at its top, two (2) 254mm-range dial gauges for settlement measurements, two (2) magnetic dial gauge holders, two (2) 1.22-meter long, 0.051-meter diameter steel rods driven 0.75 meter into the ground for dial gauge support and sixteen (16) equal weights of 160.00 kg each, has been devised. This technique has been successfully employed for the determination of the load bearing capacity of sub-soils for emplacement of 300.00 kPa INO ATM & INO LP Separators at an Oil Flow Station in the Freshwater Swamps of the Niger Delta at Ogboinbiri, Southern Ijaw Local Government Area of Bayelsa State of Nigeria. Field investigations indicated that the in-situ silty-clayey lateritic soils have undrained shear strength parameters of φ_u=6°−10° and undrained cohesion intercept (c_u) = 24.00 – 32.00 kPa, natural moisture content (w) = 36.5% ; and consistency limits of LL = 38.5%; PL = 11.6 – 13.8% . Using this modified Plate Load Tester, and testing at four (4) points situated within a designated area of 12m x 16m, the bearing capacity values of the soils which had earlier been improved upon by vibro-flotation, ranged from 431.82 to 462.57 kPa. These values were all above the designed bearing capacity of 300.00 kPa required for the placement of the Separators at the project site. This paper describes in detail the design and fabrication of the modified Plate Load Tester, its field applications using the procedures of ASTM D1194-72, field data acquisition, analysis and computations. The advantages and disadvantages of this Plate Load Testing technique over the conventional technique are also discussed.